Video systems are known to detect the driver condition and to warn him especially when he is at risk of falling asleep, which systems monitor for how long the driver keeps the eyes closed while driving (Japanese Patent No. JP-10315799) and which wake the driver by an acoustic warning sound once a threshold is exceeded, or which keep him in the awake state. A similar video system for monitoring the eyes of the driver is known from European Patent No. EP 1 418 082.